fix: replace TTS FIFO cache with LRU eviction, add database indexes

TTS audioCache now tracks lastAccess timestamp per entry and evicts
the least-recently-used entry when full (was FIFO, deleting commonly
used phrases). Adds 6 new database indexes for bets, bot type/active
filtering, payment status lookups, and tournament entries.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/game/tts.ts

@@ -120,7 +120,7 @@ const _pending = new Map<number, {
 
 // --- Audio state (main thread only) ---
 let _audioCtx: AudioContext | null = null
-const audioCache = new Map<string, AudioBuffer>()
+const audioCache = new Map<string, { buf: AudioBuffer; lastAccess: number }>()
 const MAX_CACHE = 50
 const activeSources: Set<AudioBufferSourceNode> = new Set()
 
@@ -265,7 +265,7 @@ async function _generateAndCache(text: string, profile: string): Promise<AudioBu
   if (!_workerReady) return null
   const key = _cacheKey(text, profile)
   const cached = audioCache.get(key)
-  if (cached) return cached
+  if (cached) { cached.lastAccess = Date.now(); return cached.buf }
 
   // Dedup: if already generating this exact audio, reuse the in-flight promise
   const existing = _inflight.get(key)
@@ -288,12 +288,16 @@ async function _doGenerate(text: string, profile: string, key: string): Promise<
   const buf = ctx.createBuffer(1, raw.audio.length, raw.sampleRate)
   buf.getChannelData(0).set(raw.audio)
 
-  // Evict oldest if cache is full
+  // Evict least-recently-used if cache is full
   if (audioCache.size >= MAX_CACHE) {
-    const oldest = audioCache.keys().next().value
-    if (oldest) audioCache.delete(oldest)
+    let lruKey: string | undefined
+    let lruTime = Infinity
+    for (const [k, v] of audioCache) {
+      if (v.lastAccess < lruTime) { lruTime = v.lastAccess; lruKey = k }
+    }
+    if (lruKey) audioCache.delete(lruKey)
   }
-  audioCache.set(key, buf)
+  audioCache.set(key, { buf, lastAccess: Date.now() })
   return buf
 }
 
@@ -355,7 +359,8 @@ export function kokoroSpeak(
   const key = _cacheKey(text, profileName)
   const cached = audioCache.get(key)
   if (cached) {
-    _playBuffer(cached, dest, volume)
+    cached.lastAccess = Date.now()
+    _playBuffer(cached.buf, dest, volume)
     return true
   }
   // Generate in worker — will play when ready